It is well known to form a large expanse of concrete as a series of discrete slabs separated by appropriate expansion joints. When such a structure forms the lining of a canal, reservoir, or the like, the ability of such expansion joints to remain water-tight becomes a significant issue, and provision must be made to provide some sort of joint seal.
By way of example, consider a seawater canal, perhaps on the order of 10 km long with three channels, each 30 m wide and 6 m deep. Naturally, the seal must prevent water leakage under the normal hydrostatic pressure of approximately 10 psi. Furthermore, if the channel is drained of water, the seal must remain in place despite upwardly directed ground water forces. Additionally, since the need for a resilient seal arises from the possibility of relative movement between adjacent slabs due to settlement and the like, the seal must accommodate such movement. For example, the seal may be required to accommodate horizontal displacements (expansion and contraction) of approximately 6 mm and vertical differential displacements on the order of 10-20 mm. Moreover, for longevity, the seal should be able to withstand bacterial and chemical action, ultraviolet irradiation, and extremes of temperature.
One type of prior art joint seal utilizes a resilient sealant such as a polysulfide resin to fill the gaps between slabs. The sealant adheres to the concrete slab edges to provide a water-tight joint. Unfortunately, while such seals are typically effective when initially installed, differential vertical and horizontal movement and environmental effects can cause the adhesion to break down to the point where significant leakage occurs.
The problem of retrofitting the seals on a canal or similar structure is rather different from, and typically more difficult than, the problem of designing and installing the original seals. While there are other types of seal that might be more suitable than those discussed above, they can only be installed as part of the original construction, not as a retrofit.
Thus there is presented the problem of providing a retrofit seal capable of maintaining water-tight joints over a significant range of slab movement and hydrostatic forces.